Zenith XBS344 Series, Service Manual

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3-4
ELECTRICAL TROUBLESHOOTING GUIDE
1. Power(SMPS) CIRCUIT
NO 5.3VA.
Replace the F101.
(Use the same Fuse)
Is the F101 normal?
Is the R101
normal?
Is the BD101
normal?
NO
NO
NO
NO
NO
NO
Replace the
BD101.
Replace the R101.
Is the D102
normal?
Check or Replace
the D102.
Replace the D112.
Replace the IC103.
YES
YES
YES
YES
YES
YES
YES
Is Vcc(8.5~21V) sup-
plied to IC101 Pin7?
NO
Is the D112 normal?
Is there about 2.5V
at the IC103 Vref?
Check the Main PCB
5.3VA/5.0V Line short?
(1) No 5.3VA (SYS/Hi-Fi/TUNER)
NO 12VA.
Check or Replace
the D110. Is the Vcc(13V) supplied
to (+) terminal in D115?
Check or Replace
the Motor Vcc.
Is the Vcc(12V) supplied
to (-) terminal in D115?
NO
NO
Replace the D115.
YES
YES
YES
(2) No 12VA (TO CAP, DRUM MOTOR)
NO 5.0VA.
5.3VA Line Check.
Is 5.3VA put into
the Q160 Emitter?
Is about 5V put into
the Q160 Base?
Is the Q162 Base
“H”?
NO
NO
Check the Power
Control.
NO
Check or Replace the
Q162, R157, R158, R159.
YES
YES
YES
Check or Replace
the Q162/Q160.
YES
(3) No 5.0V (SYS/Hi-Fi/TUNER)